Benefits of using high pressure grinding rolls at the Malmberget

concentratorconcentrator

Background

• 20 % increase in capacity in the concentration plantconcentration plant

• One possibility is High Pressure Grinding Roll (HPGR)

What is HPGR?

Questions to be answered

What can be expected from a HPGR in terms of increase in capacity in the p yconcentration plant?

Is it possible to save energy with a HPGR?HPGR?

Sorting plant Concentration plant

Installation of HPGR

Benefits of using HPGR

• Energy efficient• High availability• High availability• High capacity• Generating microcracks• Generating microcracks.

HPGR disadvantages

• Feed to HPGR important• Dry feed required (max 10 %• Dry feed required (max 10 %

moisture)• Choke feedChoke feed• The product must be

deagglomerated

Test on material

Photo: Erik Degerstedt and Bertil Pålsson

Results60,0

30,0

40,0

50,0

t10

(%)

-6.7+4.75-3.35+2.36-1.18+0.850-0.600+0.425Logg. (-1.18+0.850)

10,0

20,0

Logg. (-0.600+0.425)Logg. (-3.35+2.36)Logg. (-6.7+4.75)

0,00 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8

Ecs kWh/t

Beräknade produktstorlekar

100,00

50,00

60,00

70,00

80,00

90,00

ulat

iv %

-6,7mm+4,75mm-3,35mm+2,36mm-1,18mm+0,85mm

0 00

10,00

20,00

30,00

40,00

Kum

u

-0,6mm+0,425mmAlla

0,0010 100 1000 10000

Partikelstorlek µm

Calculation of capacity and specific energy

Four alternativesAlt 0: Reference. Existing circuit.Alt 1: A finer product from HPGR assumed

to give increase in capacity in concentratorAlt 2: A finer product from HPGR

bi d ith l B d W k I d icombined with lower Bond Work Index in primary grinding step assumed to give increase in capacity in concentrator

Alt 3: A finer product from HPGR pcombined with lower Bond Work Index in all three grinding steps assumed to give increase in capacity in concentrator

R l b d HPGRResults based on HPGR in open circuit

Results from calculations

• Increased capacity in concentrator with 5 – 13 %concentrator with 5 13 %

• Specific energy is lowered with 1 – 7 %

• Total power consumption increase with 4 %.

MicrocracksMicrocracksBefore pressing

After pressing

Conclusion

For HPGR in open circuit

• HPGR cannot alone increaseHPGR cannot, alone, increase the capacity by 20 % in the concentration plant

Thanks to

Supervisors Bertil Pålsson (LTU), Kent Tano (LKAB) and ÅkeKent Tano (LKAB) and Åke Sundvall (LKAB)

The end!